Speed and ease of tracheal intubation: priming with mivacurium compared with succinylcholine.

This study examined the efficacy of mivacurium priming (0.015 mg.kg-1) with five minutes between the priming and intubating doses by comparing the effects of one, two and three times the ED95 dose (0.075 mg.kg-1) of mivacurium after priming (Groups 1, 2 and 3, respectively), with a saline prime and 2 x ED95 mivacurium (Group 4) or 1 mg.kg-1 dose of succinylcholine (Group 5). The time from the intubating dose injection to intubation was measured and intubating conditions were rated on a five-point scale with 4 being optimal and 0 being failure. Mean times (+/- SEM) in seconds between the administration of the intubating dose and tracheal intubation were: 106.4 +/- 5.1, 89.6 +/- 6.7, 81.9 +/- 2.7, 169.9 +/- 7.8 and 82.9 +/- 3.5 for Groups 1-5 respectively. The times for Group 2 (2 x ED95 with priming), Group 3 (3 x ED95 with priming) and Group 5 (succinylcholine with saline) were shorter than the times of Groups 1 (1 x ED95 with priming) and 4 (2 x ED95 with saline) P < 0.05. Mean intubating condition scores (+/- SD) for the five groups respectively were 3.1 +/- 0.6, 3.4 +/- 0.6, 3.5 +/- 0.5, 3.2 +/- 0.6 and 3.8 +/- 0.4. Scores for Groups 2, 3 and 5 were higher than those of Group 1 (P < 0.05). The data demonstrated that (1) priming with mivacurium shortens the intubation time and is accompanied by good intubating conditions with doses 2x and 3x ED95, and (2) intubating times and conditions similar to those achieved with succinylcholine can be obtained using mivacurium 2x (total dose 0.150 mg.kg-1) or 3 x ED95 (total dose 0.215 mg.kg-1) with a five-minute priming interval. Priming provides an alternative technique in those clinical circumstances where succinylcholine is contraindicated.